Hak Rim Kim

The new diterpene isodojaponin D inhibited LPS-induced microglial activation through NF-kappaB and MAPK signaling pathways.

Neuroinflammation with prolonged microglial activation leads to increased levels of pro-inflammatory mediators and subsequently contributes to neuronal dysfunction and neuronal loss. Therefore, pharmacological suppression of neuroinflammation would theoretically slow the progression of neurodegenerative disease. In this study, we investigated the anti-inflammatory effects and possible mechanisms of isodojaponin D (19-hydroxy-1alpha,6-diacetoxy-6,7-seco-ent-kaur-16-en-15-one-7,20-olide), a new diterpene isolated from Isodon japonicus against lipopolysaccharide(LPS)-induced microglial activation in BV2 cells. Results from RT-PCR and Western blot showed that pretreatment with isodojaponin D (5 and 10 microg/ml) prior to treatment with LPS (1 microg/ml) significantly decreased LPS-induced production of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in a dose-dependent manner. In addition, LPS-induced pro-inflammatory cytokines, including IL-1beta, IL-6, and TNF-alpha, were also decreased by pretreatment with isodojaponin D. This effect was accompanied by a decrease in translocations of Nuclear Factor-KappaB (NF-kappaB) p50 and p65 from the cytoplasm to the nucleus and by a decrease in I kappaB (IkappaB) degradation. In addition, pretreatment with isodojaponin D significantly attenuated LPS-induced mitogen-activated protein kinase (MAPK) activation. Taken together, these results suggest that isodojaponin D suppressed LPS-induced microglial activation and production of pro-inflammatory mediators by inhibition of the NF-kappaB signaling pathway and phosphorylation of MAPKs. These results suggest that isodojaponin D could play a beneficial role in treatment of neurodegenerative disease.

Beneficial effects of phosphatidylcholine on high-fat diet-induced obesity, hyperlipidemia and fatty liver in mice.

AIMS Soybean-derived PC is an essential cell membrane phospholipid that is composed of unsaturated fatty acids, including oleic acid. The present study aimed to evaluate the potential alleviation effects of soybean PC on high fat diet (HFD)-induced obesity and its related complications. MAIN METHODS We fed C57BL/6 mice a HFD for 12 weeks and administered PC orally for 8 or 12 weeks at different doses. At the end of the experiment, blood was prepared for biochemical analysis and leptin ELISA. Aorta, epididymal and mesenteric fat and liver were removed surgically, weighed and observed for histological or immunohistochemical changes. KEY FINDINGS PC significantly prevented body weight gain and lipid accumulation and alleviated hyperlipidemia by decreasing triglyceride (TG) and total cholesterol (TC) levels and the atherogenic index in serum or by increasing the HDL/TC ratio. Aortic apoE expression and serum leptin levels were suppressed by PC treatment in the HFD-induced obese mouse model. Elevated serum aspartate aminotransferase and alanine aminotransferase levels in HFD-fed mice were decreased in the PC groups. PC treatment significantly decreased HFD-induced liver weight and hepatic lipid accumulation. SIGNIFICANCE PC treatment alleviated HFD-induced obese status and obesity-related complications such as hyperlipidemic changes that induce cardiovascular disease and NAFLD.

Direct detection of tetrahydrobiopterin (BH4) and dopamine in rat brain using liquid chromatography coupled electrospray tandem mass spectrometry.

A simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of tetrahydrobiopterin (BH4) and dopamine in rat brain using epsilon-acetamidocaproic acid (AACA) as an internal standard. Proteins in the samples were precipitated with acetonitrile and then the supernatants were separated by a Sepax Polar-Imidazole (2.1 × 100 mm, i.d., 3 μm) column using a mixture of 10mM ammonium formate in acetonitrile/water (75:25, v/v) as the mobile phase at a flow rate of 300 μl/min. Quantification was performed on a triple quadrupole mass spectrometer employing electrospray ionization with the operating conditions as multiple reaction monitoring (MRM) and positive ion mode from m/z 242.1 → 166.0 for BH4, m/z 154.1 → 90.0 for dopamine and m/z 174.1 → 114.0 for AACA (IS). The total chromatographic run time was for 5.5 min. The method was validated for the analysis of samples: the limit of detection was 10 ng/g. The calibration curve was linear between 10-2000 ng/g for BH4 (r(2)=0.995) and 10-5000 ng/g for dopamine (r(2)=0.997) in the rat brain. Thus, good correlated LC-ESI/MS/MS results were obtained and found to be a powerful tool for the quantitative analysis of BH4 and dopamine in the rat brain.

The effect of quercetin-3-O-β-D-glucuronopyranoside on indomethacin-induced gastric damage in rats via induction of mucus secretion and down-regulation of ICAM-1 expression

The mechanism of the protective effect of quercetin-3-O-β-D-glucuronopyranoside (QGC) from the leaves of Rumex aqauticus on indomethacin (IND, a representative NSAID)-induced gastric damage in rats was investigated. Pre-treatment with QGC significantly attenuated IND-induced gastric mucosal injury. An increase in myeloperoxidase (MPO) activity and expression of intercellular adhesion molecule (ICAM)-1 protein and mRNA expression of the pro-inflammatory cytokines tumor necrosis factor-α and interleukin-1β, as well as a decrease in gastric mucus secretion were detected in the gastric mucosa of IND-treated rats. QGC reversed the side effect of IND on MPO activity and mucus production. Furthermore, QGC pre-treatment notably decreased ICAM-1 protein and mRNA expression of the pro-inflammatory cytokines, suggesting that QGC protection from IND-induced damage is associated with increased gastric mucus secretion, inhibition of free radical production by activated neutrophils via ICAM-1, and pro-inflammatory cytokine downregulation.

Long-term exposure to 835 MHz RF-EMF induces hyperactivity, autophagy and demyelination in the cortical neurons of mice.

Radiofrequency electromagnetic field (RF-EMF) is used globally in conjunction with mobile communications. There are public concerns of the perceived deleterious biological consequences of RF-EMF exposure. This study assessed neuronal effects of RF-EMF on the cerebral cortex of the mouse brain as a proxy for cranial exposure during mobile phone use. C57BL/6 mice were exposed to 835 MHz RF-EMF at a specific absorption rate (SAR) of 4.0 W/kg for 5 hours/day during 12 weeks. The aim was to examine activation of autophagy pathway in the cerebral cortex, a brain region that is located relatively externally. Induction of autophagy genes and production of proteins including LC3B-II and Beclin1 were increased and accumulation of autolysosome was observed in neuronal cell bodies. However, proapoptotic factor Bax was down-regulted in the cerebral cortex. Importantly, we found that RF-EMF exposure led to myelin sheath damage and mice displayed hyperactivity-like behaviour. The data suggest that autophagy may act as a protective pathway for the neuronal cell bodies in the cerebral cortex during radiofrequency exposure. The observations that neuronal cell bodies remained structurally stable but demyelination was induced in cortical neurons following prolonged RF-EMF suggests a potential cause of neurological or neurobehavioural disorders.

Induction of Autophagy in the Striatum and Hypothalamus of Mice after 835 MHz Radiofrequency Exposure.

The extensive use of wireless mobile phones and associated communication devices has led to increasing public concern about potential biological health-related effects of the exposure to electromagnetic fields (EMFs). EMFs emitted by a mobile phone have been suggested to influence neuronal functions in the brain and affect behavior. However, the affects and phenotype of EMFs exposure are unclear. We applied radiofrequency (RF) of 835 MHz at a specific absorption rate (SAR) of 4.0 W/kg for 5 hours/day for 4 and 12 weeks to clarify the biological effects on mouse brain. Interestingly, microarray data indicated that a variety of autophagic related genes showed fold-change within small range after 835 MHz RF exposure. qRT-PCR revealed significant up-regulation of the autophagic genes Atg5, LC3A and LC3B in the striatum and hypothalamus after a 12-week RF. In parallel, protein expression of LC3B-II was also increased in both brain regions. Autophagosomes were observed in the striatum and hypothalamus of RF-exposed mice, based on neuronal transmission electron microscopy. Taken together, the results indicate that RF exposure of the brain can induce autophagy in neuronal tissues, providing insight into the protective mechanism or adaptation to RF stress.

Quantification of Neurotransmitters in Mouse Brain Tissue by Using Liquid Chromatography Coupled Electrospray Tandem Mass Spectrometry

A simple and rapid liquid chromatography tandem mass spectrometry method has been developed for the determination of BH4, DA, 5-HT, NE, EP, Glu, and GABA in mouse brain using epsilon-acetamidocaproic acid and isotopically labeled neurotransmitters as internal standards. Proteins in the samples were precipitated by adding acetonitrile, and then the supernatants were separated by a Sepax Polar-Imidazole (2.1 mm × 100 mm, i.d., 3 μm) column by adding a mixture of 10 mM ammonium formate in acetonitrile/water (75 : 25, v/v, 300 μl/min) for BH4 and DA. To assay 5-HT, NE, EP, Glu, and GABA; a Luna 3 μ C18 (3.0 mm × 150 mm, i.d., 3 μm) column was used by adding a mixture of 1% formic acid in acetonitrile/water (20 : 80, v/v, 350 μl/min). The total chromatographic run time was 5.5 min. The method was validated for the analysis of samples. The calibration curve was linear between 10 and 2000 ng/g for BH4 (r2 = 0.995) , 10 and 5000 ng/g for DA (r2 = 0.997) , 20 and 10000 ng/g for 5-HT (r2 = 0.994) , NE (r2 = 0.993) , and EP (r2 = 0.993) , and 0.2 and 200 μg/g for Glu (r2 = 0.996) and GABA (r2 = 0.999) in the mouse brain tissues. As stated above, LC-MS/MS results were obtained and established to be a useful tool for the quantitative analysis of BH4, DA, 5-HT, NE, EP, Glu, and GABA in the experimental rodent brain.

Differential Effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine on Motor Behavior and Dopamine Levels at Brain Regions in Three Different Mouse Strains

Developing an animal model for a specific disease is very important in the understanding of the underlying mechanism of the disease and allows testing of newly developed new drugs before human application. However, which of the plethora of experimental animal species to use in model development can be perplexing. Administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a very well known method to induce the symptoms of Parkinsons disease in mice. But, there is very limited information about the different sensitivities to MPTP among mouse strains. Here, we tested three different mouse strains (C57BL/6, Balb-C, and ICR) as a Parkinsonian model by repeated MPTP injections. In addition to behavioral analysis, endogenous levels of dopamine and tetrahydrobiopterin in mice brain regions, such as striatum, substantia nigra, and hippocampus were directly quantified by liquid chromatography-tandem mass spectrometry. Repeated administrations of MPTP significantly affected the moving distances and rearing frequencies in all three mouse strains. The endogenous dopamine concentrations and expression levels of tyrosine hydroxylase were significantly decreased after the repeated injections, but tetrahydrobiopterin did not change in analyzed brain regions. However, susceptibilities of the mice to MPTP were differed based on the degree of behavioral change, dopamine concentration in brain regions, and expression levels of tyrosine hydroxylase, with C57BL/6 and Balb-C mice being more sensitive to the dopaminergic neuronal toxicity of MPTP than ICR mice.

Determination of Platycodin D and Platycodin D3 in Rat Plasma Using Liquid Chromatography-Tandem Mass Spectrometry

Platycodon grandiflorum has long been used as a traditional oriental medicine for respiratory disorder. Platycodin D (PD) is known as the main component isolated from the root of PG. A simple and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantitation of PD in rat plasma. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization and multiple reaction monitoring in positive ion mode. The total chromatographic run time was 4.0 min, and the calibration curves of PD were linear over the concentration range of 50–10,000 ng/mL in rat plasma. The coefficient of variation and relative error at five QC levels were 1.0 to 8.8% and 0.7 to 8.7%, respectively. After a single oral administration of 500 mg/kg and a single intravenous administration of 25 mg/kg of 3% PD extract (a PG extract including 3% of PD), platycodin D and platycodin D3 were detected and pharmacokinetic parameters were estimated. The oral bioavailability of platycodin D and platycodin D3 was 0.29% and 1.35% in rats at 500 mg/kg of 3% PD extract of PG, respectively. The present method can be applied to pharmacokinetic analysis of platycodins and platycosides of the PG.

Neuroprotective Effect of Ginseng against Alteration of Calcium Binding Proteins Immunoreactivity in the Mice Hippocampus after Radiofrequency Exposure

Calcium binding proteins (CaBPs) such as calbindin D28-k, parvalbumin, and calretinin are able to bind Ca2+ with high affinity. Changes in Ca2+ concentrations via CaBPs can disturb Ca2+ homeostasis. Brain damage can be induced by the prolonged electromagnetic field (EMF) exposure with loss of interacellular Ca2+ balance. The present study investigated the radioprotective effect of ginseng in regard to CaBPs immunoreactivity (IR) in the hippocampus through immunohistochemistry after one-month exposure at 1.6 SAR value by comparing sham control with exposed and ginseng-treated exposed groups separately. Loss of dendritic arborization was noted with the CaBPs in the Cornu Ammonis areas as well as a decrease of staining intensity of the granule cells in the dentate gyrus after exposure while no loss was observed in the ginseng-treated group. A significant difference in the relative mean density was noted between control and exposed groups but was nonsignificant in the ginseng-treated group. Decrease in CaBP IR with changes in the neuronal staining as observed in the exposed group would affect the hippocampal trisynaptic circuit by alteration of the Ca2+ concentration which could be prevented by ginseng. Hence, ginseng could contribute as a radioprotective agent against EMF exposure, contributing to the maintenance of Ca2+ homeostasis by preventing impairment of intracellular Ca2+ levels in the hippocampus.